This topic contains 10 replies, has 1 voice, and was last updated by 
josh November 13, 2020 at 9:44 pm.
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joshQ: Cost goes up a lot with each engine unit? Is it necessary to use many?
A: It would be a new smaller design, with a plan to produce a larger number. They might even be all electric. What are the intrinsic features of the engine cost? One can play with different parameters & see. I thought about 4 for list shooting down & for stability.
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joshThe idea I wrote about the other week – curving the angle from inflow to outflow of the turbo fan is also something that could potentially generate additional lift in that scenario.
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joshThe blades are big – 225 r/min is not very fast.
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joshMore pep talk about this topic:
Note 1: The Chinook is very fuel inefficient, but out hope is to only be fuel inefficient for VTOL liftoff, while capturing plane characteristics for most of the flight.
Note 2: I like the idea of keeping the parked object in a truck size/shape format. Here’s an idea for a helicopter like VTOL mechanism in that format:
An pointed roof/arrow head shape along the center ridge line of the roof, above the roof, with an open vent on the bottom; it has 2 longitudinal spinning turbines that push air 45 degrees down to either side, so it creates an updraft into the arrow from below and achieves some vertical contribution of thrust as well. The blades of a conventional helicopter are large & positioned above the helicopter body. They push a lot of air to the side & it creates an updraft that pulls the blade apparatus & body upwards. The idea here is that the 2 long, turbines (spinning in opposite rotations) have a largish surface area & push air sideways & down from a above the truck. This creates both updraft & thrust. The directions of each are achieved with vents with holes. What I am imagining is shaped sort of like a big horn sheep in section profile, with the turbine somewhere close to the highest elevation in each horn. In transverse section it extends the length of the truck, so it’s comparable in size to a pair of copter blades. The horns have strategic holes for air intake, especially where the head would be. Hopefully this plan provides an almost apples to apples comparison to the helicopter in which more air is moved at greater velocity, in a comparable manner. So at least the same sort of load bearing should be possible. Is it so? Relevant design constraints are a) no part of the blade should travel faster than the speed of sound, and b) to the extent that the air is already moving in the direction of the blade push or at low pressure then less force is being transferred to the air movement & the rotor is less efficient. The air flow should be designed to maximize the amount of air sucked up from below to push the craft upwards prior to being propelled away & down. Perhaps some kind of a horn shaped profile leading in from below.
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joshMy thought is that it is possible to design Turbofans in such a way that the local geometry of the engine & spinning turbines stays fixes while the orientation of the engine & the air/intake outake geometry varies dynamically in different phases of flight/ground maneuvering.
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josh4+ thrusters in some reasonable configuration can slightly pitch the craft on takeoff/landing in a way that makes them balanced around the center of gravity.
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joshVarying the shape/direction of input/exhaust, orientation in space, & plane velocity/wind – what is the overall contribution to lift/thrust/drag from different turbines? Very complicated. Is there a FE simulation way to calculate for any set of fully modeled choices?
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josh3 different potentially positive physical contributions from the engine:
a) thrust from the exhaust direction
b) low pressure in the direction we want to go
c) rushing air pressure bending at the turn between input direction & exhaust directionOn a C-130, in-flight, a+ b) are big factors & c) is non-existent. A helicopter is all b), done in a different way than a C-130. Can we use tilting engines, electric preferably but maybe some gas, that use a+b+c in flight & do something different in take-off-landing…either only a)+c) are signific or b) functions in a helicopter rather than a turbofan way ??
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joshInterpret F=ma as the average acceleration of the mass of air being displaced to help force our craft in an upwards direction. If we use only a + c then want a horn shape to draw air from below & the exhaust in a different spot. Or if it’s a+b then we want a shape above that evokes a larger vortex. Either way, involving a larger mass of air helpful.
This isn’t a tweedledee/tweedledum of lift.
What is a shape with a small fast prop that simulates a larger one for lift? Perhaps the smaller blad is sandwiched between a large, gently inverted moon & smaller, centered disk, so displaced air is routed to the side & down, away. The intake/ouflow is rotationally contoured, as a copter.So there are 3 concepts for generating f=ma – copter, copter simul, & bottom thruster.
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joshI looked online for research related to the question of how to optimize smooth air/fluid flow in dynamically bendable ducts. I didn’t see anything specific. I suggest consideration of a design that features interlocked sections of some kind of a membrane that can be pulled taught over each shape configuration of the duct.
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